6.b. Command Reference

The following is the entire list of commands and keywords in the Maestro script language. The “stack effect” column specifies how many numbers are consumed and added to the stack. For example, the PLUS command takes off two numbers and returns one; so it has a stack effect of -2,+1. Commands with special effects will be marked with a *.

Keywords

keyword	stack effect	description
BEGIN	none	marks the beginning of a loop
ENDIF	none	ends a conditional block IF…ENDIF
ELSE	none	begins the alternative block in IF…ELSE…ENDIF
GOTO label	none	goes to the label label (define it with label:)
IF	-1	enters the conditional block if the argument is true (non-zero) in IF…ENDIF or IF…ELSE…ENDIF
REPEAT	none	marks the end of a loop
SUB name	none	defines a subroutine name
WHILE	-1	jumps to the end of a loop if the argument is false (zero)

Control commands

command	stack effect	description
QUIT	none	stops the script
RETURN	none	ends a subroutine

Timing commands

command	stack effect	description
DELAY	-1	delays by the given number of milliseconds
GET_MS	+1	gets the current millisecond timer (wraps around from 32767 to -32768)

Stack commands

command	stack effect	description
DEPTH	+1	gets the number of numbers on the stack
DROP	-1	removes the top number from the stack
DUP	+1	duplicates the top number
OVER	+1	duplicates the number directly below the top, copying it onto the top
PICK	-1,+1	takes a number n between 0 and 63, then puts the nth number below the top onto the stack (0 PICK is equivalent to DUP)
SWAP	a,b → b,a	swaps the top two numbers
ROT	a,b,c → b,c,a	permutes the top three numbers so that the 3rd becomes the top and the others move down one position
ROLL	-1,*	takes a number n, then permutes the top n+1 numbers so that the n+1th becomes the top and all of the others move down one
PEEK	-1,+1	(Mini Maestro 12, 18, and 24 only) takes a number n, then copies the nth value on the stack (measured from the bottom) to the top of the stack
POKE	-2,+1	(Mini Maestro 12, 18, and 24 only) takes a number n, then removes the next value from the stack and puts it at the nth location on the stack (measured from the bottom)

Mathematical commands (unary)

These commands take a single argument from the top of the stack, then return a single value as a result. Some of these have equivalents in C (and most other languages), listed in the “C equivalent” column below. We use “false” to mean 0 and “true” to mean any non-zero value. A command returning “true” always returns a 1.

command	C equivalent	description
BITWISE_NOT	~	inverts all of the bits in its argument
LOGICAL_NOT	!	replaces true by false, false by true
NEGATE	–	replaces x by -x
POSITIVE	none	true if and only if the argument is greater than zero
NEGATIVE	none	true if and only if the argument is less than zero
NONZERO	none	true (1) if and only if the argument is true (non-zero)

Mathematical commands (binary)

These commands take two arguments from the top of the stack, then return a single value as a result. The order of the arguments, when important, is the standard one in mathematics; for example, to compute 1 – 2, you write “1 2 MINUS”. These commands all have equivalents in C (and most other languages), listed in the “C equivalent” column below.

command	C equivalent	description
BITWISE_AND	&	applies the boolean AND function to corresponding bits of the arguments
BITWISE_OR	|	applies the boolean OR function to corresponding bits of the arguments
BITWISE_XOR	^	applies the boolean XOR function to corresponding bits of the arguments
DIVIDE	/	divides the arguments
EQUALS	==	true if and only if the arguments are equal
GREATER_THAN	>	true if and only if the first argument is greater than the second
LESS_THAN	<	true if and only if the first argument is less than the second
LOGICAL_AND	&&	true if and only if both arguments are true
LOGICAL_OR	||	true if and only if at least one argument is true
MAX	none	selects the greater of the two arguments
MIN	none	selects the lesser of the two arguments
MINUS	–	subtracts the arguments
MOD	%	computes the remainder on division of the first argument by the second
NOT_EQUALS	!=	true if and only if the arguments are not equal
PLUS	+	adds the arguments
SHIFT_LEFT	<<	shifts the binary representation of the second argument to the left by a number of bits given in the second argument (without wrapping)
SHIFT_RIGHT	>>	shifts the binary representation of the first argument to the right by a number of bits given in the second argument (without wrapping)
TIMES	*	multiplies the arguments

Servo, LED, and other output commands

command	stack effect	description
SPEED	-2	sets the speed of the channel specified by the top element to the value in the second element (see Section 4.b)
ACCELERATION	-2	sets the acceleration of the channel specified by the top element to the value in the second element (see Section 4.b)
GET_POSITION	-1,+1	gets the position of the channel specified by the top element
GET_MOVING_STATE	+1	true if any servos that are limited by speed or acceleration settings are still moving
SERVO	-2	sets the target of the channel specified by the top element to the value in the second element, in units of 0.25 μs
SERVO_8BIT	-2	sets the target of the channel specified by the top element to the value in the second element, which should be a value from 0 to 254 (see the Mini SSC command in Section 5.e)
LED_ON	none	turns the red LED on
LED_OFF	none	turns the red LED off (assuming no errors bits are set)
PWM	-2	(Mini Maestro 12, 18, and 24 only) enables the PWM output channel, with the period specified by the top element and the on time specified by the second element, both in units of 1/48 μs (see Section 4.a for more information about PWM)
SERIAL_SEND_BYTE	-1	(Mini Maestro 12, 18, and 24 only) removes the top number from the stack, interprets it as a single byte, and sends that byte to the TTL serial output (TX)